No fixed amount for the sauce, use as much as you like.
Wash the shrimp thoroughly and pat them dry.
Thinly slice the onion and bell pepper.
Cut the chicken breast into bite-sized pieces.
Place a tortilla on an ovenproof pan.
Spread a thin layer of tomato sauce on top.
Add chicken breast, shrimp, onion, and bell pepper.
Sprinkle with mozzarella cheese.
Bake at 200°C (392°F) for 10 minutes.